1. Field of the Invention
The present invention relates to a waste fluid treating apparatus attached to a processing apparatus such as a cutting apparatus for cutting a workpiece such as a semiconductor wafer to treat a waste fluid generated from a process fluid supplied in processing.
2. Description of the Related Art
In a semiconductor device fabrication process, a plurality of crossing division lines called streets are formed on the front side of a substantially disk-shaped semiconductor wafer to partition a plurality of areas where devices such as ICs and LSIs are respectively formed. The semiconductor wafer is cut along the streets to divide these areas from each other along the streets, thereby producing the individual semiconductor devices. Further, also in an optical device wafer, the front side of a sapphire substrate is partitioned into a plurality of areas by a plurality of crossing streets, and a gallium nitride compound semiconductor or the like is layered in each of these partitioned areas to thereby form an optical device in each area. Such an optical device wafer is cut along the streets to obtain individual optical devices such as light emitting diodes and laser diodes, which are widely used for electrical equipment.
Cutting of the semiconductor wafer and the optical device wafer mentioned above along the streets is usually performed by using a cutting apparatus called a dicer. This cutting apparatus includes a chuck table for holding a workpiece such as a semiconductor wafer, cutting means including a cutting blade for cutting the workpiece held on the chuck table, and process water supplying means for supplying a process water to the cutting blade, wherein the process water is supplied to the cutting blade under rotation by the process water supplying means, thereby cooling the cutting blade, and the process water is also supplied to a cut area of the workpiece to be cut by the cutting blade in a cutting operation.
In the cutting operation, a waste fluid left after cutting silicon or gallium nitride compound semiconductor contains chips due to cutting. Such a waste fluid containing the chips of semiconductor materials causes environmental pollution, and the chips are therefore removed from the waste fluid by using a waste fluid treating apparatus. Thereafter, the waste fluid is reused or put to disposal (see Japanese Patent Laid-open No. 2004-230527, for example).
The waste fluid treating apparatus mentioned above includes a waste fluid tank for storing a waste fluid generated from a process fluid supplied in processing by a cutting apparatus, a waste fluid pump for sending the waste fluid stored in the waste fluid tank, waste fluid filtering means for filtering the waste fluid sent by the waste fluid pump to obtain a fresh water, a fresh water tank for storing the fresh water obtained by the waste fluid filtering means, a fresh water pump for sending the fresh water stored in the fresh water tank, and pure water generating means including an ion exchanger for purifying the fresh water sent by the fresh water pump to obtain a pure water.